This invention relates generally to conveyors and, more particularly, to extendable conveyors for loading products into, or unloading products from, a truck trailer or the like.
Extendable conveyor units are typically implemented for loading and unloading truck trailers or the like in order to minimize the distance which the product being loaded or unloaded must be manually carried. Extendable conveyors in use today may have two, three or four extendable units, or extensions, in order to achieve the desired extended length for reaching a forward portion of the truck trailer, while still providing a relatively compact conveyor when it is retracted on the loading dock.
In order to provide an extendable conveyor which may retract into a relatively compact position on the loading dock, extendable conveyors typically include a base unit which is anchored to a warehouse or loading dock floor and one or more extendable units which are nested within the base unit and within each of the other inwardly positioned extendable units. The base unit and the extendable units may include horizontal support channels in order to guide the outwardly positioned extendable units and to bear the cantilever loading of the extendable units as they extend therefrom. Because the extendable units are nested within one another, the number of extendable units are typically limited, since additional units would either excessively limit the width of the outermost unit or result in a conveyor which is taller and requires a greater amount of floor space.
Generally, it is desirable to maximize the ratio of the width of the conveyor belt to the overall width of the base unit, such that there is a minimal difference between the two dimensions. In order to provide a larger space on which to place the cargo being loaded or unloaded, it is also important to maximize the width of the conveyor belt and outer conveying surface. Because each extendable unit is nested within the other inwardly positioned units, the width of the outermost nested units will be less than the width of the base structure and the inner units. Accordingly, additional extensions may be excessively narrow and may not accommodate the cargo on their conveying surface. Although such a concern may be resolved by including wider inner units and a wider base unit to accommodate a wider outermost extension, this is also undesirable, since the greater width of the base unit interferes with the floor space of the warehouse.
An additional concern with increasing the number of extendable units of the conveyor is that each unit requires a substantial amount of vertical space within the next inwardly positioned unit. This further results in the conveying surface of the base structure being at a greater height in order to accommodate each additional extendable unit. Such a design may not be feasible, since the conveying surface may have to accommodate an already existing supply or take-away conveyor which is installed at the warehouse or loading dock.
It is also generally desirable to maximize the ratio of the fully extended conveyor to the retracted length of the conveyor, in order to minimize the intrusion of the conveyor in the warehouse when it is not in use, while still providing a maximum extended length to reach into the truck trailers. Accordingly, extendable conveyors with longer booms or extendable units may not be desirable, since such a design would also require substantially more floor space in its retracted position when the conveyor is not in use. The longer, retracted units would then interfere with floor space that is required for people or machinery to move about within the warehouse.
Other concerns arise with respect to existing extendable conveyors in that such conveyors may be unable to extend a desired length due to the implementation of longer delivery trucks or other restrictions which may prevent the trucks from backing all the way up to the dock on which the extendable conveyor is mounted. Extensions have been proposed which may be attachable to an existing two, three or four unit extendable conveyor in order to achieve a greater length without having to replace the entire conveyor. Some extensions may be mounted on an outermost end of the outer extendable unit in order to provide an additional length to the extendable conveyor. However, such extensions do not nest within the inwardly positioned units when retracted and may not retract completely with the extendable conveyor. Such extensions may thus adversely affect the floor space requirements for the conveyor in the warehouse. Furthermore, these proposed extensions require a separate power source to operate a separate drive system for driving a separate conveyor belt along the additional extension. These separate conveying belts are typically of a reduced width with respect to the conveying portions and belt of the existing conveyor in order to allow the additional unit to rest upon the existing conveyor.
Therefore, there is a need in the art for an extendable conveyor which may extend farther into a truck trailer, without adversely affecting the width of the conveying surface or the floor space taken up by the extendable conveyor when it is retracted. Furthermore, the overall height of the conveying surface of the base structure should not be affected, in order to implement the conveyor adjacent to already existing supply or take-away conveyors in place at the warehouse or loading dock. Furthermore, there should be provided the capability to retro fit existing extendable conveyors with extensions in a manner which does not require a narrower conveying surface and which retracts fully with respect to a base unit.
The present invention is intended to provide an extendable conveyor which may extend farther into a truck trailer or the like over previously proposed conveyors, without adversely affecting the floor space required for such a conveyor and the retracted length and/or width of the conveying surface of the conveyor.
According to an aspect of the present invention, an extendable conveyor for conveying articles comprises a base structure, at least one extendable unit adjustably positioned between a retracted position and an extended position relative to the base structure, an extendable boom at least partially nested within the extendable unit and a support system for the extendable boom. The extendable unit has an upper portion, at least a portion of which defines a first conveying surface. The extendable boom is adjustably positionable between a retracted and extended position relative to the extendable unit. The extendable boom defines a second conveying surface. The support system includes at least one forward support member and a cantilever support member. The cantilever support member engages the upper portion of the extendable unit to cantileverly support the extendable boom relative to the extendable unit. The forward support member engages and supports the extendable boom and allows a greater width of the second conveying surface relative to a width of the first conveying surface.
In one form, the extendable boom comprises a pair of side members which are insertable into the extendable unit and a conveying mechanism which is pivotally attached to a forward end of the side members and extends over top of the extendable units. The forward support member is rotatably attached to the extendable unit such that a lower surface of the side members engages the forward support member for rolling contact therewith.
In another form, the extendable boom nests substantially within the forward extendable unit. The forward support members comprise a roller carriage which provides rolling engagement between a lower track along opposite sidewalls of the forward extendable unit and a lower portion of a pair of opposite side members of the extendable boom. The roller carriage provides support for the extendable boom relative to the forward extendable unit by moving forwardly along the forward extendable unit as the extendable boom is extended and rearwardly along the forward extendable unit as the extendable boom is retracted.
According to another aspect of the present invention, an extendable conveyor for conveying articles comprises a base structure, at least one extendable unit adjustably positioned between a retracted position and an extended position relative to the base structure and an extendable boom which is at least partially nested within the extendable unit. The extendable boom is adjustably positioned between a retracted position and an extended position relative to the extendable unit. The extendable unit has a first conveying surface which has a first width. The extendable boom is operable to extend outwardly from the extendable unit such that the extendable boom is cantileverly supported by the extendable unit. The extendable boom has a second conveying surface which has a second width. The second width is at least as great as the first width of the first conveying surface.
According to yet another aspect of the present invention, an extendable conveyor comprises a base structure, at least one extendable unit adjustably positioned between a retracted position and an extended position relative to the base structure, an extendable boom which extends and retracts within the extendable unit and a support system for the extendable boom. The extendable unit has a first conveying surface and the extendable boom has a second conveying surface. The support system includes a cantilever support roller and a roller carriage. The roller carriage includes at least one roller which is operable to roll relative to the extendable unit and the extendable boom such that the roller carriage moves outwardly relative to the extendable unit as the extendable boom moves outwardly relative to the roller carriage and the extendable unit. The extendable boom moves approximately twice the distance that the roller carriage moves relative to the extendable unit.